From the earliest days of lathe turning, there has been a requirement attaching one end of a piece of wood or other material to a rotatable arbor, normally termed the head stock of the lathe. The axis of the head stock arbor defines the center line for turning what ever object is to be produced. In the case of short, flat objects, such as bowls, only the head stock arbor is used to act as total support for the workpiece to be turned. For longer objects, a tail stock with the center aligned with the axis is used to hold the opposite end of the blank, its only rotatable connection to the tail stock.
The classic form of attachment of the workpiece or blank to the rotating arbor is a metal faceplate made up of metal such as die cast zinc or in some certain cases, machined steel or aluminum. The faceplate typically will have a circular flat surface attached to a central cylinder designed to mate with and be secured to the arbor shaft of the head stock. The faceplate member is usually attached to the head stock arbor by engaging threads. In some cases, keys and keyways or set screws are used to secure to face place onto the rotating arbor.
The flat surface of the faceplate is usually attached to the workpiece by a plurality of fasteners such as screws which enter from the rear face through holes located between the central axis and the periphery, but usually the holes are three in number and spaced 120.degree. apart.
The faceplate must be rigid and strong enough, not only to support the workpiece along or with the tail stock, but also must hold the workpiece securely during the initial chisel cut, which usually requires a series of cuts to remove the corners of the workpiece, which is often rectangular or square, to bring the workpiece to a circular diameter. The intermittent cutting of the chisel as each corner is removed in sequence produces great vibration and there can be no possibility of the workpiece blank separating from the faceplace.
In certain cases, the workpiece is secured to the faceplate by adhesives without a positive mechanical interconnection, as in the case of screws. In such case, the need is for the faceplate to be rigid, unyielding and additionally have good bonding properties with the adhesive used. This is very important.
One of the banes of the turner is the inability to make any cuts near the faceplate for fear of striking or cutting into the metal faceplate with immediate damage or destruction of the chisel and the faceplate. This usually results in unwanted post turning detailing which are time consuming and never can produce the same smooth results as a fully turned piece.
Another limitation on the existing metallic faceplates is that they cannot be used effectively to chuck a pre-turned and finished piece, nor to mount any sphere starting blank to make further turning operations. There is no good way to assure that the center line or turning axis of the lathe matches an actual diameter of an existing sphere.
Also existing metallic faceplates are not useful for receiving and holding any base of an object already turned and having a diameter less than the screw location diameter connection. Existing metallic faceplates are not suitable for adhesive bonding of small diameter objects. Existing metal faceplates generally do not provide any effective means for indexing of objects, for example, for fluting.